Data storage systems are arrangements of hardware and software that include storage processors coupled to arrays of non-volatile storage devices, such as magnetic disk drives, electronic flash drives, and/or optical drives, for example. The storage processors service storage requests, arriving from host machines (“hosts”), which specify files or other data elements to be written, read, created, deleted, and so forth. Software running on the storage processors manages incoming storage requests and performs various data processing tasks to organize and secure the data elements stored on the non-volatile storage devices.
Some data storage systems employ cloud-based storage resources in addition to local storage. For example, EMC CloudArray supports cloud-based storage of LUNs (Logical UNits) and makes those LUNs available using conventional block-based protocols, such as iSCSI (Internet Small Computer System Interface), Fibre Channel, and the like. CloudArray supports in-cloud snapshots and is compatible with Amazon S3 (Simple Storage Services). CloudArray supports numerous cloud providers, such as Microsoft Azure, Dell EMC ECS (Elastic Cloud Storage), Virtustream, and many others, and supports both public cloud and private cloud solutions.
Some data storage systems aggregate data objects in structures known as NAS (Network Attached Storage) servers, which may also be referred to herein as virtual data movers, or “VDMs.” Each NAS server is a collection of user file systems, settings, and one or more network servers, such as a CIFS (Common Internet File System) server and/or an NFS (Network File System) server, which provide host access to the user file systems. Settings may be stored within one or more file systems of the NAS servers themselves, such that NAS servers are self-contained. Many NAS servers may operate together in a single storage processor and within a single operating system environment.